/Engine/Source/Runtime/Landscape/Classes/LandscapeInfo.h
Landscapes are a bit special in that they contain derived data within their source data, which can be updated on-the-fly depending on many external factors (e.g. a procedural edit layer can invalidate some data on load). Depending on project preference, the modifications can be either automatically taken into account (leading to landscape actors becoming dirty on load) or manually by the user (i.e. invalidated landscape actors are not made dirty on load but the user is required to save the modified actors through a Build menu action). Therefore we use these 2 functions as a replacement to Modify or MarkPackageDirty in cases where we don't know if the modification was initiated by the user : SeeUObject::Modifytrue if the object could not be marked dirty but has been added to the list of ModifiedPackages
bool ModifyObject ( [UObject](API\Runtime\CoreUObject\UObject\UObject) * InObject, bool bAlwaysMarkDirty )